Adenylyl cyclase isoforms and vasopressin enhancement of agonist-stimulated cAMP in vascular smooth muscle cells

Abstract

The influence of arginine vasopressin (AVP) on agonist-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) accumulation was investigated in vascular smooth muscle cells (VSMC) cultured from rat thoracic aorta. Incubation of VSMC with AVP for 60 s produced a 2- to 2.5-fold enhancement of isoproterenol-induced cAMP formation. AVP also increased cAMP stimulation by the prostaglandin I2 analogue iloprost. The effect of AVP to enhance agonist-stimulated cAMP formation was completely inhibited in cells pretreated with a selective antagonist of V1 vasopressin receptors but was not affected by blockade of V2 receptors. Inhibition of protein kinase C activation failed to alter the action of AVP to potentiate cAMP stimulation, but treatment of cells with calmodulin antagonists significantly attenuated this effect of the peptide. Moreover, depletion of Ca2+ stores with thapsigargin decreased AVP enhancement of isoproterenol-stimulated cAMP by > 70%. The action of AVP to increase cAMP stimulation was also demonstrated in freshly isolated strips of rat aorta where treatment with peptide produced a twofold increase in isoproterenol-stimulated cAMP formation. RNA blot analysis indicated expression in VSMC of mRNA encoding type III adenylyl cyclase, a Ca(2+)-calmodulin-sensitive isoform of the effector. Furthermore, when detergent-solubilized membrane extract was subjected to calmodulin affinity chromatography, a peak of adenylyl cyclase activity was identified which had affinity for calmodulin matrix in the presence of Ca2+. The results indicate that AVP activates V1 receptors in VSMC to enhance agonist-stimulated cAMP formation by a Ca(2+)-calmodulin-dependent mechanism and suggest that type III adenylyl cyclase may provide a focal point in the VSMC for cross talk between constrictor and dilator pathways.

Pituitary Adenylate Cyclase-activating Polypeptides Directly Stimulate Sympathetic Neuron Neuropeptide Y Release through PAC1 Receptor Isoform Activation of Specific Intracellular Signaling Pathways

“…For example, agonist-stimulated increased IP 3 production also has been shown to enhance cAMP formation by a calcium-calmodulindependent mechanism (66,67). Contrary to expectation, inhibition of phospholipase C augmented PACAP-mediated cAMP production.…”

Adenylyl Cyclase Isoform–Selective Regulation of Vascular Smooth Muscle Proliferation and Cytoskeletal Reorganization

“…Because the "control" rat vascular smooth muscle cells endogenously express the AC6 isoform, but not the AC1, AC2, AC4, AC7, AC8, or AC9 isoforms, 19,20 we used short interfering RNA (siRNA) strategies directed against the AC6 isoform to explore the impact of silencing of AC6 expression on control as well as AC6-overexpressing cells. As shown in Figure 2B, siRNA targeted against AC6 selectively reduces the heterologous expression (detected by Western blots for the Flag-tagged AC introduced by adenoviral transduction) of AC6 without impact on the expression of AC2, indicating the specificity of the siAC6 reagent.…”

Intracellular Pathways of V1 and V2Receptors Activated by Arginine Vasopressin in Rat Hippocampal Neurons

“…These results indicate that AVP(4 -9) alone, which stimulates the V 1 receptor, can induce cAMP accumulation through IP 3 production in the hippocampal neurons. In vascular smooth muscle cells, AVP alone induces cAMP accumulation by activating the Ca 2ϩ /CaM-sensitive adenylate cyclase (type 3) expressed in the smooth muscle cells through the V 1 receptors and modulates the isoproterenolstimulated cAMP accumulation (56). Brinton and McEwen (17) have also reported that the facilitative effect of AVP on norepinephrine-induced cAMP accumulation depends on [Ca 2ϩ ] o .…”

“…Interestingly, it has been reported that ␥-aminobutyric acid-induced current was also modulated by an increase of intracellular free Ca 2ϩ released from intracellular Ca 2ϩ storage sites but not by Ca 2ϩ influx in cultured porcine pituitary intermediate lobe neurons (59). In addition, Zhang et al (56) demonstrated that influx of Ca 2ϩ from extracellular medium appears to contribute little to the AVP-induced enhancement action of isoproterenol-stimulated cAMP accumulation in the smooth muscle cells.…”